Synthetic Biology

[Due to the increasing size of the archives, each topic page now contains only the prior 365 days of content. Access to older stories is now solely through the Monthly Archive pages or the site search function.]

June 12, 2015

Like other major automakers, Audi (and its parent Volkswagen Group) is working on meeting its medium-term regulatory requirements (e.g., in the 2020 timeframe) by reducing the average fuel consumption of its new vehicles using a combination of three primary measures: optimizing its combustion engines for greater efficiency; developing alternative drive concepts, such as hybrid, plug-in hybrid and gas-powered vehicles; and reducing total vehicle weight through lightweight construction with an intelligent multimaterial mix.

Unlike the others, however, Audi over the past few years has embarked on a comprehensive approach to developing a range of new CO₂-neutral fuels as part of its overall strategy for sustainable, carbon-neutral mobility: Audi e-fuels. Audi’s basic goal is to combine renewable energy (e.g. solar and wind), water and CO2 to produce liquid or gaseous fuels with a very low carbon intensity. Audi e-fuels are intended to use no fossil or biomass sources; do not compete with food production; and are 100% compatible with existing infrastructure.

May 26, 2015

Last week, Audi and its partner Global Bioenergies announced that the first batch of renewable isooctane—which Audi calls “e-benzin”—using Global Bioenergies’ fermentative isobutene pathway (sugar→isobutene→isooctane) had been produced and presented to Audi by Global Bioenergies. (Earlier post.)

Global Bioenergies, founded in 2008, has developed a synthetic isobutene pathway that, when implanted in a micro-organism, enables the organism to convert sugars (e.g., from starch and biomass) via fermentation into gaseous isobutene via a several-stage enzymatic process. However, following the delivery of the first renewable isooctane, Reiner Mangold, Audi’s head of sustainable product development, said that Audi was “now looking forward to working together with Global Bioenergies on a technology allowing the production of renewable isooctane not derived from biomass sources”—i.e., using just water, H2, CO2 and sunlight.

April 15, 2015

Researchers at The University of Manchester, Imperial College London and University of Turku have made an advance toward the renewable biosynthesis of propane with the creation of a new synthetic pathway in E. coli, based on a fermentative butanol pathway. An open access paper on the work is published in the journal Biotechnology for Biofuels.

In 2014, members of the team from Imperial College and the University of Turku had devised a synthetic metabolic pathway for producing renewable propane from engineered E. coli bacteria, using pathways based on fatty acid synthesis. (Earlier post.) Although the initial yields were far too low for commercialization, the team was able to identify and to add essential biochemical components in order to boost the biosynthesis reaction, enabling the E. coli strain to increase propane yield. Yields, however, were still too low.

New engineered metabolic pathways in yeast enable efficient fermentation of xylose from biomass

March 05, 2015

Researchers with the Energy Biosciences Institute (EBI), a partnership that includes Berkeley Lab and the University of California (UC) Berkeley, have introduced new metabolic pathways from the fungus Neurospora crassa into the yeast Saccharomyces cerevisiae to increase the fermentative production of fuels and other chemicals from biomass. An open access paper on the work is publised in the journal eLife.

While S. cerevisiae is the industry mainstay for fermenting sugar from cornstarch and sugarcane into ethanol, it requires substantial engineering to ferment sugars derived from plant cell walls such as cellobiose and xylose. The new metabolic pathways enable the yeast to ferment sugars from both cellulose (glucose) and hemicellulose (xylose)—the two major families of sugar found in the plant cell wall—efficiently, without the need of environmentally harsh pre-treatments or expensive enzyme cocktails.

February 11, 2015

A team led by researchers from the University of Illinois at Urbana−Champaign has, for the first time, integrated the fermentation pathways of both hexose and pentose sugars from biomass as well as an acetic acid reduction pathway into one strain of the yeast Saccharomyces cerevisiae using synthetic biology and metabolic engineering approaches.

The engineered strain co-utilized cellobiose, xylose, and acetic acid to produce ethanol with a substantially higher yield and productivity than the control strains. The results showed the unique synergistic effects of pathway coexpression, the team reported in a paper in the journal ACS Synthetic Biology.

Researchers discover bacteria could be rich source of terpenes

December 24, 2014

Researchers at Kitasato University in Japan, Brown University in the US, and colleagues in Japan have found that bacteria could be a rich source of terpenes—natural compounds common in plants and fungi that can be used to make drugs, food additives, perfumes, and other products, including advanced fuels (earlier post, earlier post).

Terpenes are responsible for the essential oils of plants and the resins of trees. Since the discovery of terpenes more than 150 years ago, scientists have isolated some 50,000 different terpene compounds derived from plants and fungi. Bacteria and other microorganisms are known to make terpenes too, but they’ve received much less study. The new research, published in an open access paper in the Proceedings of the National Academy of Sciences, shows that the genetic capacity of bacteria to make terpenes is widespread.

December 02, 2014

In 2012, researchers at the US Department of Energy’s Joint BioEnergy Institute (JBEI) engineered Escherichia coli (E. coli) bacteria to overproduce from glucose saturated and monounsaturated aliphatic methyl ketones in the C11 to C15 (diesel) range from glucose. In subsequent tests, these methyl ketones yielded high cetane numbers, making them promising candidates for the production of advanced biofuels or blendstocks. (Earlier post.)

Now, after further genetic modifications of the bacteria, they have managed to boost the E.coli’s methyl ketone production 160-fold. A paper describing this work is published in the journal Metabolic Engineering.

September 03, 2014

Researchers from the University of Turku in Finland, Imperial College London and University College London have devised a synthetic metabolic pathway for producing renewable propane from engineered E. coli bacteria. Propane, which has an existing global market for applications including engine fuels and heating, is currently produced as a by-product during natural gas processing and petroleum refining. A paper on their work is published in Nature Communications.

The new pathway is based on a thioesterase specific for butyryl-acyl carrier protein (ACP), which allows native fatty acid biosynthesis of the Escherichia coli host to be redirected towards a synthetic alkane pathway. ​Although the initial yields were low, the team was able to identify and to add essential biochemical components in order to boost the biosynthesis reaction, enabling a the E. coli strain to increase propane yield, although the amounts are still far too low for commercialization.